This invention relates to an automatic weighing apparatus and method wherein the weight and volume of articles in a package can be held within preset allowable limits.
Some articles, such as cornflakes and potato chips, experience widely different degrees of swelling because of such processing conditions as applied temperature and material mixture. Such articles therefore differ in shape and size and vary greatly in apparent specific gravity. They also tend to crumble. When weighing out these articles and then packaging them, there are instances where the volume of the packaged product is too large or too small, even though the weight of the articles in the bag or package is equal to a target value or closest to the target value within preset limits. In other words, the change in volume of the packaged articles is inversely proportional to the change in apparent specific gravity. Since the capacity of a package receiving the articles generally is fixed, too small a product volume in comparison with the package size gives the consumer the impression of a weight shortage. On the other hand, too large a product volume can lead to an improper seal because the package will be too full, and can cause the articles to overflow from the package and impair the packaging process. Accordingly, in weighing out articles, it is required that both the volume and weight of the articles introduced into a package be held within preset allowable limits.